This study was conducted to estimate heritabilities and genetic correlations on economic traits in Korean Native Ogol Fowl. The data analysis were the record of 450 pullets produced from 150 dams and 20 sires of Korean Native Ogol Fowl raised at Chungnam National University from June 18, 1987 to April 6, 1989. The results obtained are summarized as follows ； 1. The average body weights at 8 and 24 weeks,300 and 500 days of age were 514.54, 1490.96, 1753.47 and 2013.31g respectively, The age of first egg was 179.19 days, and the number of egg Produced to 300 and 500 days of age were 80.12 and 162.82 e89s, respectively. The egg weight at first egg, 300 and 500 days of a8e were 40.03 and 49.92 and 55.59g, respectively. 2 The heritability estimates based on the variance of sire, dam and combined components were 0.441-0.661, 0.120-0.490, 0.345-0.465 for body weight； 0.365, 0.207 and 0.282 for age at first egg； 0.354-0.362, 0.204-0.230 and 0.279-0.296 for number of egg production: 0.259-0.464, 0.512-0.633 and 0.386-0.540 for egg weight, respectively. 3. The genetic correlations coefficients of economic traits were as follows: the coefficients between body weight with age at first egg, number of egg Production and egg weight were 0.539-0.617, -0.520-0.157 and 0.180-0.754； between age at first egg with number of egg production and egg weight were -0.717 and 0.552-0.587； between number of egg production and egg weight was -0.383-0.381, respectively.

An experiment was carried out to investigate the effects of dietary energy levels and protein feeding systems on the performance of laying hens. Total 960 White Leghorn pullets were alloted in 10 treatments consisted of 1 metabolizable energy levels (2,900 and 2,600 kcal/kg) and 5 protein feeding systems (17-17-15%, 17-15-13%, 15-15-15%15-15-13% and 15-13-13% in phase I, II and/or III, respectively) from 20 to 80 weeks or age. As metabolizable energy level increased from 2,600 to 2.900 kcal/kg of diet, e99 Productions in phase I and II were not different but decreased in phase III. Egg weight was not different, but daily feed intake and viability were decreased in phase I, II and III. Feed conversions in phase I and II were improved but in phase III it was not different. On the other hand, as dietary Protein level increased from 13 to 17%, egg production and egg weight were increased, and feed conversion was improved , but daily feed intake and viability were not affected by the dietary protein level. For the laying period of 60 weeks, metabolizable energy level of 2,600 kcal/kg of diet and 17, 15 and 13% dietary protein levels in phase I, II and III, respectively, were considered to be adequate to support the optimum productivity.

Two broiler experiments were carried out to determine whether supplementation of zeolite in the diet would affect broiler performance and economical efficiency. Day old male broiler chickens of Abor Acres strain were used. In the first experiment,60 birds were distributed into f groups of 10 birds each. Three groups of chickens were randomly placed on one of the following single-stage (0-6wks) experimental diets； control diet (non-supplemented) or 2% zeolite supplemented diet (supplemented to the control). In the second experiment,216 birds were distributed into 24 groups of 9 birds each. Eight groups of chickens were randomly placed on one of the 3 two-stage diet (starter；0-4wks, finisher；5-7wks)；control diet ( , non-supplemented), 2% zeolite diet (：isocaloric and isonitrogenous as ) and 2% zeolite supplemented diet (, supplemented to the control). Birds were housed in the batteries, and feeds and water were fed ad libitum. The results of Experiment 1 showed that birds fed control diet were heavier than those fed 2% zeolite supplemented diet up to 4th wks of age. However, birds fed the latter grew more at 5th and 6th wk. Overall weight gain, feed intake and feed efficiency were not significantly different. The results of Experiment 2 showed that there were no significant differences in weight gains, feed intakes and feed efficiencies among treatments during starter, finisher to overall period. The moisture levels in excreta of the birds were significantly (P＜0.01) less when zeolite was included in the diets and those in excreta significantly (P ＜ 0.01) increased as the ambient temperature increased. Economical efficiency expressed in fed cost (won) required per kg weight gin were 346.55 (T),348.34 ( ) and 359.85 ().

Pretreatment of egg white and ion exchange resins was attempted to separate lysozyme from egg white efficiently. Apparent viscosity of egg white could be decreased to 3cp by homogenization for 30 minutes at 2, 000rpm and ultrasonication for 45 minutes. The result of testing adsorption capacity of lysozyme was as follows； CM-Sephadex C-25 ＞Duolite C464＞Amberlite C-50＞Dowex MSC-1＞Amberlite IRC-50＞Amberlite IRC-84. Although CM-Sephadex C-25 showed highest adsorption capacity of lysozyme, egg white could not eluted easily. Duolite Cf64 was selected based on relatively high lysozyme adsorption and good egg white eluting property for separation of egg white lysozyme. Na form of Duolite C-464 was most effective on adsorption of Iysozyme. To separate lysozyme from egg white efficiently rinse buffer and eluting solution were selected 0.1M sodium phosphate buffer at pH 6.5 and 10% ammonium sulfate respectively. After separating lysozyme from egg white, foaming power of egg white was decreased to 85.3%. Color of egg white gel was not changed while hardness of egg white gel was decreased by 30% after separating lysozyme. However, elasticity of egg white gel was increased by 13% in lysozyme-separated egg white.

Culled laying hens used in this study were Arbor acres, which reared to S 35 days old on commerical formula feed for chicken. Liver, gizzard, breast and thigh muscles separated from each carcass, and total lipid was extracted and fractionated to neutral, phospho and glycolipid and then fatty acid composition were analyzed. Liver had the highest level of. total lipid, and breast tissue had the least among tissues tested. The neutral, phospho and glycolipid contents of total lipid had more thigh, breast and gizzard than other tissues, respectively. The major fatty acid in total and neutral lipid were palmitic, stearic, oleic and linoleic acid. And the major fatty acid in phospholipid was palmitic, stearic, oleic, linoleic, arachidonic and docosahexaenoic acid, and palmitic, palmitoleic, stearic, oleic and linoleic acid in case of glycolipid. The fatty acid contents of neutral, phospho and glycolipid in total lipid had more oleic, docosahexaenoic and linoleic acid than other lipid, respectively. Contents of unsaturated fatty acid of total and neutral lipid were comparatively high in thigh, and phospho and glycolipid were high in breast and liver, respectively. Contents of Polyunsaturated fatty acids were comparatively high in phospholipids than other lipids.

A total of 9, 012 cases was submitted for diagnosis of chicken diseases to Veterinary Research Institute, Rural Development Administration from domestic chicken farms during 18 years from 1971 to 1988. Of them, 6, 181 cases diagnosed as the infectious disease were investigated for the detection rate of infections on basis of you, season , and chicken age. The results obtained were summarized as followings：1. Detection rate or the infections was lowest as 49.3% in the year 1973, and highest as 78.6% in 1985 (average 68.6%). 2. Of infections detected, bacterial diseases were most frequent (32.6%), and followed in order by viral (26.3%), parasitic (7.7%), and fungal diseases (2.1%) in geneal. 3. The most frequently detected bacterial diseases in order of prevalence were mycoplasmosis (8.8%), colibacillosis (8.5%), and staphylococcosis (5.8%), and followed by salmonellosis pullorum disease , yolk sac disease, and salpingitis (0.8-1.5%). 4. In viral diseases, 7.5% of infections detected was lymphoid leukosis and 7.2%-Marek's disease, 4.4%-Newcastle disease, 2.0%-infectious laryngotracheitis, 1.7%-infectious bursal disease, and 1.0%-avian encephalomyelitis, while detection rate of infectious bronchitis, egg drop syndrome '76, and inclusion body hepatitis was less than 1.0%, respectively. 5. The most prevalent parasitic disease was coccidiosis (4.5%), followed by ascariasis (1.4%). The detection rate of other parasitic diseases including leucocytozoonosis, black head , heterakiasis, and ectoparasitosis was very as 0.2-0.7%, respectively： In fungal diseases, 2.0% of infections was detected as aspergillosis, and followed by candidiasis (0.1%). 6. Detection rate of the infections on basis of season was somewhat higher in summer. (27.7%), and autumn (27.7%) than in winter (23.5%), and spring (21.5%) in general. In bacterial, viral, and fungal diseases, there were the similar tendencies of detection rate as in infections, while parasitic diseases were much highly detected in summer (34.3%), and autumn (39.5%) than in any other season. 7. Among bacterial diseases colibacillosis was most frequently detected in summer, and staphylococcosis in autumn. In detection rate of viral diseases, Marek's disease, infectious laryngotracheitis, and infectious bursal disease was highest in summer, lymphold leukosis, fowl pox and egg drop syndrome '76 in autumn, and infectious trachitis in winter, repectively. The majority of important parasitic diseases including coccidiosis were highly detected in summer and autumn. 8. On basis of chicken age, detection rate of infections were highest in chicken of growing period between 30 and 150 days of age (41.4%), and followed by 35.3% in laying chicken over 150 days of age, and 17.3% in chicken of brooding age under 30 days of age. Bacterial, and parasitic diseases were most frequently detected in chicken of growing period, viral diseases in chicken of growing, and laying period as nearly equal rate of detection, and fungal diseases in chicken of brooding age.